There are currently an estimated 40 000 incidences of cardiac arrest every year in Canada, most of which take place outside of hospital settings. The odds of an out-of-hospital cardiac arrest currently stand at approximately 5%. In the U.S., there are about 164 600 such instances each year, or about 0.55 per 1000 population. There is a desire to decrease these out-of-hospital incidences of cardiac arrest. Certain places, such as sports arenas, and certain individuals, such as the elderly, are at particular risk and in these places and for these people, a convenient solution may be the difference between survival and death.
Cardiopulmonary resuscitation (CPR) is a proven effective technique for medical and non-medical professionals to improve the chance of survival for patients experiencing cardiac failure. CPR forces blood through the circulatory system until professional medical help arrives, thereby maintaining oxygen distribution throughout the patient's body. However, the quality of CPR is often poor. Retention of proper CPR technique and protocol may be inadequate in most individuals and the anxiety of an emergency situation may confuse and hinder an individual in delivering proper treatment.
According to the journal of the American Medical Association (2005), cardiopulmonary resuscitation (CPR) is often performed inconsistently and inefficiently, resulting in preventable deaths. Months after the completion of standard CPR training and testing, an individual's competency at performing effective chest compressions often deteriorates significantly. This finding was found to hold true for untrained performers as well as trained professionals such as paramedics, nurses, and even physicians.
The International Liaison Committee on Resuscitation in 2005 described an effective method of administering CPR and the parameters associated with an effective technique. Parameters include chest compression rate and chest compression depth. Chest compression rate is defined as the number of compression delivered per minute. Chest compression depth is defined as how far the patient's sternum is displaced. An effective compression rate may be 100 chest compressions per minute at a compression depth of about 4-5 cm. According to a 2005 study at Ulleval University Hospital in Norway, on average, compression rates were less then 90 compressions per minute and compression depth was too shallow for 37% of compressions.
According to the same study, CPR was often administered when unnecessary or was not administered when necessary. The study found that compressions were not delivered 48% of the time when cardiovascular circulation was absent.
Positioning of the hands is another parameter that may be considered when delivering CPR. It has been found that an effective position for the hands during compression is approximately 2 inches above the base of the sternum. Hand positioning for effective CPR may be different depending on the patient. For example, for performing CPR on an infant, an effective position may be to use two fingers over the sternum.
Other studies have found similar deficiencies in the delivery of CPR. One 2005 study at the University of Chicago found that 36.9% of the time, less than 80 compressions per minute where given, and 21.7% of the time, less than 70 compressions per minute were given. The chest compression rate was found to directly correlate to the spontaneous return of circulation after cardiac arrest.
In addition to too shallow compressions, too forceful compressions may also be problematic. Some injuries related to CPR are injury to the patient in the form of cracked ribs or cartilage separation. Such consequences may be due to excessive force or compression depth. Once again, lack of practice may be responsible for these injuries.
Therefore, a device to facilitate the proper delivery of CPR in an emergency is desired. Furthermore, a device that can also be used in objectively training and testing an individual may be useful for the CPR training process and protocol retention.
Current solutions in emergency cardiac care mostly focus on in-hospital treatment or appeal mostly to medical professionals. CPR assist devices that tether to defibrillators can be found in hospitals. However, these devices are often expensive and inaccessible to the lay individual who does not have a defibrillator on hand or cannot operate such a device. Furthermore, such devices are often not portable nor are they easily accessible. Simple devices with bar graph displays indicating compression force are often cumbersome in design and non-intuitive in use. Such a device may be uncomfortable to the patient and user and often has minimal data output. Thus, misuse of such a device is probable rendering it a hindrance rather than an aid.
There are currently mechanical systems for the delivery of CPR that may be used in a hospital setting. Chest compression may be delivered through a mechanism comprising mechanical movement (e.g., piston movement or motor movement). One such device is the AutoPulse™ by Revivant Corp, which has a computer-controlled motor attached to a wide chest band that compresses the chest, forcing blood to the brain when the heart has stopped beating.
Another device is the Q-CPR™ by Philips Medical, which is used to assess CPR quality. This device includes a CPR module connected to a defibrillation system. Although not currently marketed as a training device, the Q-CPR currently exists as a resuscitation aid and has future potential as a training technology. The device includes a block that provides compression depth and rate information to a rescuer through the display on the defibrillator. The CPR module is a unit placed on the patient's chest and under the hands of the individual performing the CPR. It may be cumbersome and may not be suited for use by non-medical professionals. The device has a multitude of instrumentation, which may make it expensive. In addition, the patient's comfort and safety may be a concern when an external, rigid device such as the Q-CPR is being employed. If the user is not familiar with the device, its use could result in injury. Other devices, such the D-Padz™ by Zoll Medical employ similar technologies and thus encounter similar disadvantages.
The CPR-Ezy™ is a device that is independent from a defibrillator. It is a solid plastic block that is designed to be placed under the CPR performer's hands when performing CPR. Lights on its surface indicate the amount of force applied during a compression. Such a device may be bulky and awkward to use, and the feedback provided is limited and not quantitative. It also does not store information about the CPR performed.
Currently, a widely used technology in the training environment is the CPR mannequin. One commonly used version is the Resusci-Anne™ doll manufactured by Laerdal Medical inc. The Resusci-Anne doll allows an individual to practice his or her CPR while being subjectively monitored by an instructor. This technique relies on the observational skills of the instructor and thus may be prone to human error. Furthermore, for effective training to take place, each student must be observed separately thereby occupying a significant amount of time and decreasing the number of students who can be trained at one time. In addition, Actar Airforce Inc. develops Actar™ mannequins providing limited feedback that are currently also used in CPR training. Again, such mannequins rely on close monitoring by the instructor to be effective for training.
Similar devices have also been disclosed, for example, in U.S. Pat. Nos. 7,220,235, 7,074,199, 6,351,671, and 5,468,151. Other CPR assist devices have been disclosed in U.S. Pat. No. 5,454,779, U.S. Pat. No. 5,645,522, US 2003/036044, U.S. Pat. No. 5,496,257, US 2006/019229, and EP 162616.
It would still be desirable to provide an easy-to-use and inexpensive device to provide instruction for carrying out a proper CPR procedure for training, testing, and/or emergency situations. Such a device may be intuitive to use.